ROBBINS, Ill. — Police shot and killed an armed, black security guard who was detaining a suspect after several people were shot at a suburban Illinois bar early Sunday morning, witnesses told WGN.

Friends said Roberson was an upstanding man who had plans to become a police officer.Jemel Roberson, 26, was shot dead by a Midlothian police officer responding to a shooting inside Manny’s Blue Room Bar in Robbins, Illinois, about 4 a.m. Sunday. Witnesses said officers shot at the wrong man.

"Everybody was screaming out, 'Security!' He was a security guard," witness Adam Harris said. "And they still did their job, and saw a black man with a gun, and basically killed him."

It all began when security asked a group of drunken men to leave Manny's shortly before 4 a.m. Sunday. Witnesses said someone came back with a gun and opened fire. Security returned fire, witnesses said, and Roberson was able to detain one of the men involved outside.

Four other people, including the suspected shooter, sustained non-life threatening injuries.

"He had somebody on the ground with his knee in back, with his gun in his back, like, 'Don’t move,'" Harris said.

Soon after, according to witnesses, an officer responding to the scene shot at Roberson — killing him.

Authorities released few details Sunday.

A spokeswoman for the Cook County Sheriff's Office said Roberson had a valid FOID card, but did not have a concealed-carry license.

In a statement, Midlothian police confirmed two officers from the department responded to the scene of the shooting and that one of them opened fire.

"A Midlothian officer encountered a subject with a gun and was involved in an officer-involved shooting. The subject the officer shot was later pronounced deceased at an area hospital," Chief Daniel Delaney of the Midlothian Police Department said in a statement.

Friends said Roberson was an upstanding man who had plans to become a police officer. He was also a musician, playing keyboard and drums at several Chicago-area churches.

"Every artist he’s ever played for, every musician he’s ever sat beside, we’re all just broken because we have no answers," the Rev. Patricia Hill from Purposed Church said. "He was getting ready to train and do all that stuff, so the very people he wanted to be family with, took his life."

"Once again, it’s the continued narrative that we see of shoot first, ask questions later," the Rev. LeAundre Hill said.

The Cook County Sheriff's Office is handling the criminal investigation of the original shooting, while the State Police Public Integrity Task Force is investigating the police-involved shooting.